An Austrian man accused of imprisoning and raping his daughter has been charged with murder in connection with the death of one of the children he fathered with her.

Josef Fritzl was charged because it is suspected one of the children who died in infancy could have survived if proper medical care had been given, said Austrian prosecutors.

"Despite recognizing the baby's life-threatening situation, he deliberately decided not to intervene," prosecutors allege in a 27-page indictment filed on Thursday.

Fritzl had admitted to investigators that he burned the dead baby's body in 1996.

Fritzl, 73, a retired electrician, was also charged Thursday with rape, incest, false imprisonment and slavery.

It will mark the first time an Austrian goes on trial on a slavery charge, prosecutors said.

Locked in basement for 24 years

He has confessed to locking his daughter Elisabeth into a basement cell in Amstetten, west of Vienna, in 1984 when she was 18, and telling his wife that the girl had run away from home to join a religious cult, investigators have said.

He is accused of repeatedly raping his daughter, who gave birth to seven of his children.

"He forced Elisabeth into slave-like conditions … shut her away in the cellar and made her totally dependent on him, forcing her into sexual acts and treating her as if she was his own property," the indictment said.

The prosecutors said they will also present evidence that Fritzl threatened to kill his daughter and their imprisoned children by gassing them or through an explosion if they tried to escape.

Elisabeth, now 42, was held in the windowless cellar for 24 years before being released in April.

Fritzl facing trial next year

The case came to light when Elisabeth's 19-year-old daughter, Kerstin, became ill and was taken to hospital by Fritzl.

Suspicious of the man's behaviour, authorities compared Fritzl's DNA to a sample taken from Kerstin, and made a televised appeal for the mother to come forward with information about the girl's medical history.

Elisabeth persuaded her father to let her leave the basement for the first time in 24 years so she could meet the doctors. She and her father were detained on April 26, allowing her to finally reveal her ordeal to authorities.

Kerstin and two siblings, aged 18 and 5, had never been outside the tiny cellar where they were born. Their other three surviving siblings were raised in the home above them.

Elisabeth and the children have been receiving counselling at an undisclosed location, officials said.

In October, Fritzl was declared mentally fit to stand trial by jury. His trial is expected to begin in early 2009.

A conviction carries a maximum sentence of life imprisonment, which in Austria typically means 15 years confinement.